1. Field of the Invention
This invention relates to wireless communication systems, particularly Point to Multi-Point (PMP) and mesh or Mobile Ad-Hoc (MANET) networks.
2. Discussion of the Known Art
Point to multi-point or PMP protocol communication equipment is used in various broadband wireless systems. The systems are typically standards-based, or are certified by industry trade groups, e.g., WiMAX Forum certified, IEEE 802.16-2004, IEEE 802.16d, IEEE 802.16e-2005, IEEE 802.16e, and HIPERMAN.
Communication equipment operating under mesh or mobile ad hoc network (MANET) protocols is often used in military applications. An example of a mesh network resides in the IEEE 802.16d standard which, in addition to a mesh mode, defines a PMP mode as well. The standard allows users to select only one of either a mesh or a PMP mode of operation on the network, however.
Allocations of new radio frequency (RF) bands for operation of wireless communication networks are often difficult to obtain. Because of this and for other reasons, it would be desirable to allow multiple network topologies or protocols (e.g., PMP, and mesh or MANET) to co-exist on any one channel or channels of a wireless network without causing interference among various communications taking place under each protocol. For example, a Relay Station (RS) may need to extend the coverage of an existing wireless PMP Base Station (BS) in order to allow a given node outside the existing coverage to join the network as a new subscriber station. In such a case, the BS and the RS could link with one another using the mesh protocol to coordinate the use of network channels, and thus allow the RS to operate as a PMP base station with respect to the new subscriber station.
In another example, two military convoys each employing a PMP system may need to maintain wireless connectivity between vehicles of their respective convoys while in motion. As the base stations of the two convoys pass near one another, it would be desirable for the two base stations to implement a MANET in order to coordinate their movements with one another while maintaining their individual PMP networks.
Yet another example is a military training exercise in which it becomes necessary to gather performance data from thousands of RF collection devices in the field. Each soldier may be provided with a wireless device for relaying data collected during the exercise. Such devices would operate most efficiently in a PMP network, but some of the devices might be outside PMP coverage and need to forward data through other wireless devices (other than a BS) so as to maintain connectivity. Again, a MANET or mesh network operating simultaneously on the same channel with the PMP network would meet such a need. The foregoing examples are merely illustrative and are not intended to limit the various circumstances in which the present invention may be used advantageously.
U.S. Pat. No. 7,031,274 (Apr. 18, 2006) discloses a method of enabling systems following the IEEE 802.11 protocol to interoperate with wireless local area networks (WLANs) that use an otherwise incompatible HIPERLAN/2 standard, on a common transmission channel. Further, U.S. Pat. No. 7,133,381 (Nov. 7, 2006) describes a method by which stations operating under an enhanced, IEEE 802.11e standard, can prevent interfering transmissions from stations that do not practice the 802.11e standard.
As far as is known, no solution has been proposed for enabling PMP and mesh/MANET protocols to coexist on a wireless network (including networks that follow 802.16 or are WiMAX based) while avoiding interference to communications conducted among nodes of the network using either protocol. Note that 802.11 has a PMP protocol of sort although it is not practiced or employed. It differs from other PMP networks (such as WiMAX), however, and techniques used to allow the 802.11 PMP protocol (called PCF) would not apply to other PMP networks.